Vytautas Bacevičius (Łódź, 9 September 1905 – New York, 15 January 1970) was a Lithuanian composer of radical and modernistic leanings. Most of his works are in an atonal idiom of his own devising. He developed a theory of 'cosmic music' and came to regard Schoenberg's 12-note music as out-dated, regarding himself as a successor to Scriabin, André Jolivet and Varèse.
Bacevičius studied in Łódź with, among others, Kazimierz Sikorski and moved to Kaunas in Lithuania in 1926. In 1927 he went to Paris where he studied composition with Nikolai Tcherepnin. Returning to Lithuania in 1928 he established himself as a pianist and composer and teacher. He became the Chair of the Lithuanian Section of the ISCM. He was on tour in Argentina in 1939 when the Germans invaded Lithuania, rendering him an exile in America. He moved to the United States in 1940 and lived mainly in New York, continuing to give recitals but mainly supporting himself by teaching.
Though born in Poland, he adopted the Lithuanian form of his name (Bacevičius); he was the brother of the Polish composer Grazyna Bacewicz, to whom he dedicated his Second Symphony, della Guerra, in 1940. Bacevičius regarded his orchestral works as the most important part of his output, and composed six symphonies in all as well as four piano concertos, a violin concerto and numerous works for piano solo.